Radio antenna



C. E. BERLIN Dec. 2, 1958 RADIO ANTENNA 2 Sheets-Sheet 1 Filedliept. 3, 1953 IIIIII INVENTOR.

04424:: a. Bfkll/V Dec. 2, 1958 I c. E. BERLIN v RADIO ANIENNA Filed Sept. 3. 1953 2 Sheets-Sheet 2 IN V EN TOR.

CHARZAIS A. zSfRA/A/ United States Patent RADIO ANTENNA Charles E. Berlin, Highland Park, Mich.

Application September 3, 1953, Serial No. 378,261

22 Claims. (Cl. 343-717) This invention relates to a radio antenna and has special application to a low-impedance circuit which is non-directional in operation and highly effective as an antenna for receiving wave signals.

It is an object of the present invention to provide an antenna which can be used with moving vehicles, especially when positioned out of sight beneath the vehicle. Radio antenna now attached to automobiles are inconvenient in that they are obstructions which are subject to damage when entering a garage or passing through an area where branches of trees may contact and break the structure. Furthermore, most of these aerials are constructed for variable length and must be operated either manually or by some expensive mechanical means.

The present invention contemplates an antenna which can be located below a car and which regardless of the direction of movement of the car will have the same capacity.

It is a further object to provide a compact and concealed antenna which is just as effective for reception as any telescoping or so-called Whip antenna.

It is another object to provide an antenna construction which is suitably grounded in the connection construction to avoid static interference.

Other objects and features of the invention relating to the details of construction will be evident in the following description and claims.

Drawings accompany the disclosure, and the various views thereof may be briefly described as:

Figure 1, an elevation of the device showing the manner in which it can be mounted on a vehicle.

Figure 2, a sectional view of the antenna showing th mounting bracket and the connection cable.

Figure 3, a sectional view on line 3--3 of Figure 2.

Figure 4, a sectional view at the arrows 44 of Figure 3 showing the nature of the outer winding.

Figure 5, a detailed view of a cover locator construction.

Figure 6, a plan view of a modified construction having an inductance coupling unit.

Figure 7, a diagrammatic view of the actual relationship between the various elements of the embodiment of Figure 6.

Figure 8, a schematic view of the aerial circuit of the type illustrated in Figure 6.

Figure 9, a sectional view of a second modification utilizing an induction winding coupled with the low impedance winding.

Referring to the drawings, an automobile frame F showing a seat S schematically is shown in Figure 1. Attached to the frame is the aerial housing H supported by a bracket bolted to the frame. An areial lead cable 12 extends toward the radio under the dash of the automobile. Projecting from the aerial housing H is a stub rod 14 about 4 to 6 inches long. As mounted, the aerial is exposed to the ground.

The aerial itself is mounted in the housing H, which ice 2 is preferably formed of a shock-proof plastic, that is, a plastic material molded to shape and having a nonbrittle characteristic which will render it resistant to cracking from accidental contact with underbrush or a chance stone which might be thrown against it.

The housing H has a cover 16 molded to fit a circular opening at one side of the cylindrical housing. The housing has a circular wall 18 molded with diametrically opposed ferrules 20 and 22. One ferrule serves as a mount for the discharge stub 14. The other serves as an exit opening for the coaxial cable 12. On the inside of the housing H there is molded concentric walls 24, 26,

28, 30 and 32. The inner ring 24 has a vertical height approximately equal to the outer wall 18. The intervening walls between the inner wall and the outer wall have a vertical dimension of about one-third the vertical dimension of the housing per se. On the closed side of housing H diametrically opposed fastening lugs 36 are molded having a reentrant slot 38 to receive a J-shaped end 40 of the mounting bracket 10.

In Figure 5 there is shown a locator opening 42 adapted to co-operate with a locator projection 44 on the cover adjacent an inwardly extending annular ring 46. Also on the cover adjacent the center is a small annular rib 48 which co-operates with the inner ring 24 to add stability to the completed housing. In assembly the cover is preferably sealed to the housing either by a solvent or by other suitable means.

The conductive portions of the aerial consist of two branches leading from the co-axial lead Wire 50. One branch is an annular wrapping of spaced. coils of relatively flat ribbon copper spaced between rings 24, 26, 28, 3t) and 32. The outer ring 52 lies on the inside of the locator ring 32 but originates at 54 in contact with lead wire 50. This ring passes through an opening 56 in ring 32 and travels around the housing through a similar opening 58 in ring 30. Progressively the copper ribbon passes through opening 60 in ring 28 and then opening 62 in ring 26, until it comes to a termination around the inner ring 24 held in place by a molded lug 64.

The other branch of the aerial circuit consists of a copper ribbon of approximately the same Width as that used for the first branch but wrapped in helical fashion in the opening between the spacer 32 and the outer wall 18. An elevation of this helical wrapping 70 is shown in Figure 4. This wrapping is formed on a mandril which is removed before installation of the helical wrapping into the housing.

The coils of the winding or wrapping are preferably slightly spaced to avoid contact with each other. The winding 70 is associated electrically with the lead wire 50 at 72 and preferably within the initial portion of the winding 70 adjacent the point 72 is a short strip of Ferrite iron which increases the loading of energy in the outside coil 70 and tends to confine the lines of force. This strip of iron has been found to work satisfactorily having a dimension of about 1% inches in width, 4 inches in length and inch in thickness for a housing which is about 9 inches in internal diameter.

The device has been found to work satisfactorily when it is spaced about 5 inches from the vehicle bottom and about 8 inches from the ground. It is compact, inexpensive and out of sight and provides machine efficiency without the necessity of any physical or mechanical shifting thereof. In other words, it is an all-direction antenna.

A ribbon length which is found to be satisfactory is about 7 feet, the internal coil or branch being about 4 feet in length and the outside or helical coil being about 3 /2 feet in length, the ribbon being about 1 /2 inches in width.

A modified form of the invention is shown in Figures 6 to 8 wherein an annulus housing is shown having an inner wall 80 and an outer wall 82, the annulus being enclosed by bottom wall 84 and a top wall 86 (see Figure 7). A coil winding 90 comparable to the winding 70 of Figure 4 is disposed around the outside wall of the annulus. p

A cylindrical recess 92 is formed in the housing be tween the inner and outer walls to receive a coil winding 94. This coil is actually two coils, a primary and secondary. The primary section 96 preferably has the turns wound in adjacent position, and the secondary portion preferably has the turns wound a basket-weave style. 7 The coil 94 is associated with the winding 98 as shown diagrammatically in Figure 8. One end of coil 94 is connected to one end of winding 90. The other end of winding 90 is connected to the middle of coil 94, and the other end of coil 94 is connected to the lead As a result, the two coils are closely coupled, and the overall result is a broad resonation and a low dis tributed capacity. When the broadcast band of the car radio is tuned from the low to the high end, optimum gain is noticeably good at any frequency.

It is noted that the antenna coil 90 is of a very low impedance type and the matching coil 9% is of higher impedance. This is necessary because of the high impedance of the input circuit of the standard car radio. This arrangement gives a much needed, little distributed capacitance in the circuit of approximately 17 micromicrofarads.

The combined distributed capacity then of the com-* plete antenna circuit and the lead in using approximately feet cable lead in adds up to not over 85 micrornicrofarads, keeping it within the range of the tracking of the antenna trimmer. As an example, the winding 96 has a. capacitance of 195 mrnfd. and the winding 98 has a capacitance of 55 mmfd. Due to the conductive and in ductive relationship of these coils, the combined capacitance is about 16.8 mmfd. The entire coil resonates at approximate frequency of 1,345 kc. and peaks in a rather broad, flat top curve which will give both satisfactory selectivity and good power transfer.

The modification shown in Figure 9 is somewhat similar to the modification of Figure 6 with the exception that the inductive windings are arranged around the inner wall of the annulus. The housing of the device is composed of two identical parts 110 which join together face to face to form the complete annulus. Walls 112 provide opposed grooves for locating the low impedance ribbon type winding 90.

The high capacitance windings illustrated diagrammatically at 96 and 98 in Figure 8 are prefabricated around a cardboard core 114, the lower capacitance winding being shown at 116 and the higher capacitance winding being shown at 118. Prior to the closing of the housing the wound coils are installed around one of the center walls 120, and the circuit is completed by joining the coils and the windings. One end of coil 1.16 is joined to the low impedance winding 90 by a short jumper 122. The other end of winding 116 is joined to the other end of the winding 90 by a jumper 124. This same end of the winding 90 is also joined to one end of the winding 118 by a jumper 126, and the other end of winding 118 is connected at 128 to the conducting lead 130 of the coaxial cable. The housings 118 may then be joined together in sealed relation. At the same time the static elimination stub rod 132 is inserted at 134 in contact with i the coil 190, and the coaxial cable is mechanically sup ported at the opposite side of the housing in a metal sleeve 136, which is preferably grounded to the frame of the vehicle in which the device is installed.

A supporting hanger bracket 140 has the free ends passing through a portion of the two housings, joining them, mechanically locking the two housings together, and providing means for attaching the device to the vehicle frame. The coils 96 and 98 and the corresponding coils 116 and 118 are closely coupled coils for optimum transfer of energy.

The stub rod 14 of Figures 1 and 6 and the stub rod 132 of Figure 9 are formed of aluminum or a conductive alloy of rust-resistant material about 3 /2 inches in length and serve to discharge static voltage of the interference type into the free air at the distal end. In normal operation of a vehicle, static charges build up as a result of tire motion, spring action and the contact of passengers on the seats. This static charge will be gradually dissipated through the stub rods to prevent static interference.

As previously pointed out, the horizontal spiral is sensitive to receiving radio frequency signals normally in all directions. The physical height of the turns of the outside coil represents the vertical height (electrically) of the antenna. Thus, the antenna is vertically polarized though the loops or the turns lay horizontal in fiat spiral. The co-axial cable, of course, has the braided metal sheath which is grounded at the radio end.

It has been found that the antenna above described has one volt greater sensitivity than the average whip antenna on a bench test. On a vehicle the antenna has at least the same voltage rating as a whip antenna, which is the most sensitive in present-day use.

I claim:

1. An antenna for the reception of radio frequency waves which comprises a spiraled winding of spaced convolutions on a vertical axis formed of flat, ribbon-like conductive material, and a second winding surrounding the first spiral, said second winding being formed of a fiat, ribbon-like conductive material disposed around a circular axis concentric with said spiral winding, and means connecting one end of each of said windings to serve as a lead Wire.

2. A device as defined in claim 1 in which the two windings are housed in spaced relation in a non-conductive sealed protective case.

3. A device as defined in claim 1 in which the two windings are housed in spaced relation in a non-conductive sealed protective case having an annulus chamber disposed on a vertical axis relative to a vehicle to receive said windings, and means to support said case and said windings adjacent the under portion of a vehicle.

4. An antenna for receiving radio frequency waves comprising two windings of flat, conductive, ribbon-like material, each connected at one end to a lead wire, one of said windings comprising a spiral of spaced convolutions on one axis and the other of said windings comprising a spiraled coil disposed around a circular axis concentric with said first axis and surrounding said first coil.

5. A device as defined in claim 4 in which a core of ferrite iron is disposed through a portion of said second winding to increase the load of energy in the outside coil.

6. A device as defined in claim 4 in which a stub rod projects in a direction normal to the axis of said first winding in an electrical relation with said second windlng.

7. A device as defined in claim 4 in combination with a vehicle and means for supporting said device on said vehicle to provide a non-dircctional radio antenna.

8. A device as defined in claim 4 in combination with a non-conductive sealed protective housing having an annulus chamber and disposed around said annulus on at least one wall thereof to space the respective convolutions of said windings.

9. An antenna assembly for radio reception and the like adapted for use particularly on moving vehicles which comprises a closed, relatively flat, annular container formed of relatively thin material and having spaced concentric, axially extending walls and spaced annular walls extending between said axially extending walls to provide a substantially annular chamber, a lead cable extending into said chamber, and a plurality of windings supported by the walls of said chamber, oneof said windings comprising a toroidal coil of helically wound conductive ribbon supported in substantially parallel relation to at least one of the axially extending walls.

10. An antenna as defined in claim 9 wherein said container is made of a plastic material.

11. An antenna as defined in claim 9 including a static rod electrically connected to one of said windings and projecting from the interior of said container to the exterior, said rod being made of a conductive alloy of rustresistant material.

12. An antenna for receiving radio frequency waves, comprising a lead wire, a low impedance toroidal winding of helically Wound conductive ribbon, a high impedance winding composed of close coupled coils, said lead wire, said first winding, and said coils being connected in a closed circuit with one coil being paralleled electrically with said first winding and the other coil being in series electrically in said closed circuit.

13. An antenna as defined in claim 12 in combination with and housed in a toroidal shell, said shell comprising identical halves, each said half comprising spaced concentric inner and outer walls extending axially, and an annular Wall joining said inner and outer walls, said halves being joined in sealed relation to form a closed annular chamber.

14. An antenna as defined in claim 13 including means for supporting said first winding adjacent the outer wall of said shell, and means for supporting the second winding adjacent the inner wall of said shell.

15. An antenna as defined in claim 13 including a support bracket, said bracket having means for transfixing and locking together the halves of said toroidal shell 16. An antenna as defined in claim 12 in which the coils of the high impedance winding have relative individual capacitance greater than 3 to 1 and a combined capacitance of a value much less than the lowest capacitance coil.

17. An antenna as defined in claim 16 in which the coil of least capacitance is parallel electrically with the first winding.

18. An antenna as defined in claim 12 in which the coils of the high impedance winding have respective capacitance ratings of about 195 mmfds. and mmfds., and a combined effective capacitance of about 17 mmfds.

19. An antenna for radio reception and the like which comprises an annular container formed of non-conductive material, a series of spaced connected rings of fiat conductive material wound concentric to the axis of the container and within the container, and a lead wire extending through said container to one end of said connected rings, said rings being encircled by a spiraled winding of flat conductive material positioned in spaced relation to said rings connected also to said lead wire substantially at the point of connection of said rings.

20. The combination set forth in claim 19 including a core of ferrite iron disposed through a portion of said spiraled winding of flat conductive material.

21. The combination set forth in claim 1 including a core of ferrite iron disposed in a portion of said second winding.

22. The combination set forth in claim 9 including a core of ferrite iron disposed in one end of said toroidal coil.

References Cited in the file of this patent UNITED STATES PATENTS 1,792,964 Brooks et al. Feb. 17, 1931 1,875,358 Sola Sept. 6, 1932 2,383,286 Beers Aug. 21, 1945 2,594,115 Berney Apr. 22, 1952 FOREIGN PATENTS 430,548 Great Britain June 20, 1935 

